With the spread of network communication, a system in which a user in a remote place can display a picture (such as a moving picture, a still picture, or an intermittent quasi-moving picture having consecutive still pictures in a time series manner) picked up by a camera on a screen by using a client device such as a personal computer or a mobile tool is put into operation.
Such a system is utilized in various uses. For example, such a system is utilized as a surveillance system for monitoring an intruder or an abnormality in a management subject (see, for example, JP-A-2003-274383).